Drawers are often mounted within cabinets using ball bearing slides. Such slides permit easy access to the interior of the drawer. The slides maintain the drawer in a horizontal position regardless of how far the drawer is withdrawn from the cabinet.
Occasionally, a drawer must be removed from the cabinet, for example for repair or maintenance. Therefore, the slides preferably include means for allowing the drawer to be readily removed from the cabinet. However, the slide must also have means for preventing accidental or unintended disengagement of the drawer when the drawer is fully extended. Also, because the drawer slides must typically withstand many years of repetitive opening and closing, there is a need for drawer slides which continue to operate smoothly over extended periods of use. All drawer slides must endure severe industry performance testing. For example, one common test for drawer slides requires slide mechanisms to withstand both 15,000 two-inch travel cycles and five 80% travel cycles in response to a 15 pound pull while the drawer carries up to a 100 pound load.
Previous designs for drawer slides encountered many disadvantages in operation. Prior slides had a disconnect latch secured to one guide or member of the slide to prevent unintentional disengagement of another slide member. Removing drawers was previously accomplished by pushing down on an arm of the latch, thereby rotating the latch to pivot about a rivet or an extruded post encompassed by a rivet, providing space for the slide member to be disengaged.
A prior design for a drawer slide assembly with a pivoting disconnect latch is shown in FIG. 1. The slide member 10 has a longitudinal channel 14 comprising top and bottom slide retainers 12, 16. The pivoting style latch 20 is attached to the channel 14 using a rivet 42 in a counterbored ring 40.
As shown in FIG. 1a, on either side of the rivet 42 is an annular upwardly protruding extruded post 44. The rivet head extends over the tops of the extruded post 44; thus, the post 44 prevents the rivet head 43 from contacting the interior wall 41 of the counterbored right 40. One of ordinary skill in the art will recognize that the bottom of the rivet head 43 is tightly clamped against the top of the extruded post 44. This structure is intended to prevent the rivet head from bearing against the latch, which would prevent the latch from returning to its normal position after pivoting. Consequently, the dimensions of the depth and height of the extruded post 44 are critical to proper function of the prior art latch of FIG. 1. Even minute errors in these dimensions will cause problems in operation of the prior art latch.
One of ordinary skill in the art will understand that FIGS. 1 and 1a omit an intermediate slide member with guide block, ball bearings, and a second longitudinal channel, which are omitted for clarity. An operational slide would comprise an assembly of all the above.
The pivoting style latch 20 of FIG. 1 comprises a lever 22 formed unitarily with a counterbored ring 40 and an intermediate arm 28. When a user of the slide wishes to disconnect the slide, lever 22 is depressed using finger pressure. The lever and ring then pivot counterclockwise or clockwise depending on their orientation in the cabinet, about the extruded post 44 and rivet 42, when the lever 22 is depressed. The longitudinally proximal arm 24 moves counterclockwise, providing space for the inner longitudinal channel with guide block to clear the normally abutting face of the wall 26. Thus both the lever 22 and the arm 24 move counterclockwise towards the intermediate arm 28. Consequently the horizontal aperture 30 compresses or decreases in size when the lever 22 moves toward the intermediate arm 28. The depressed lever position 50 is shown in phantom indicating the position of the lever when depressed by finger pressure.
The pivoting of ring 40 about the extruded post 44 causes the latch to malfunction if the rivet head is secured too tightly over the extruded posts and bears against latch 20. Thus the pivoting style latch 20 may fail to return to its non-impacted position after the extended use which drawer slides are subjected to.
Prior latches also produced excessive noise in operation due to impact of a slide member on the latch and the inability of prior latches to absorb impact pressure. Limiting the travel of slide members using a stop is well understood by those skilled in the art as shown in Papp U.S. Pat. No. 4,560,212. Using a prior latch, when intermediate or outer slide members are stopped by the wall 26 of the latch of FIG. 1, the impact is noisy due to the rigid construction of the pivoting style latch. The FIG. 1 design does not have a means for absorbing the shock energy on the latch or rivet created when a slide member is stopped by the wall 26. In prior designs, all the load is transmitted throughout the latch which increases the risk of mechanical failure of the latch or guide block 46. In addition, sufficiently strong impact pressure on the wall 26 may cause the rivet 42 to be sheared off channel 14. The pivoting style design also requires precise parameters in the extruded post height, rivet clinch, and recess depth and diameter. Thus, manufacturing controls must insure only slight deviations in the dimensions of the recess, extruded post and rivet.
Consequently, prior designs for disconnect latches can be expensive and complex to manufacture. There is also a need for a drawer slide which promotes smooth, noise-free movement of the disconnect latch. Accomplishing this without complex manufacturing controls is advantageous. It would also be desirable that the latch function correctly even after years of repetitive opening and closing of the drawer.